Vibration surveys are commonly conducted on rotating and reciprocating equipment or machines to anticipate maintenance scheduling. Currently, two known techniques are used for the vibration monitoring of machines in industrial plants. The most common techique employs a portable analog meter which is carried to machine locations within a plant for making the vibration measurements. The meter sensor is mechanically connected to the machine being analyzed, and the meter provides a readout of the overall vibration level of the machine. This reading gives an indication of the magnitude of such machine vibration. The technician will normally write down the machine vibration readings and take this data to a skilled engineer who will analyze the information to determine if a machine is vibrating louder than usual. Inasmuch as a single overall measurement of the vibration magnitude is provided, this information can be unreliable. For example, the technician may have made a faulty measurement, or of no consequence may mask pertinent information.
A second state of the art approach for collecting machine vibration data, employs a tape recorder which records the vibration sound. The data sound is recorded on a portable tape recorder which is normally a bulky machine. This recording is normally taken back to a computer, for purposes of reviewing the characteristics of the machine vibration. This method is generally more accurate than the analog meter method since it provides "loudness" information together with information regarding how the machine was vibrating. This method, however, is expensive and time consuming. It can take several hours to accurately measure one machine in a plant which may have several or even several hundred machines, and particularly where a machine has a plurality of measurement points. Thus, in a plant employing numerous machines, a very intensive effort must be undertaken to gather the machine vibration data.
In accordance with various features of the present invention, a light weight and portable measuring device has been developed which serves to collect data in a reliable and rapid manner. The instrument is microprocessor based and is used in combination with a base computer which maintains a data base, provides for exception reporting and implements the detection and diagnosis of problems. The vibration levels for a given measurement are stored in digital form in the instrument's memory, and numerous measurements can be simultaneously stored. Moreover, data can be compressed by carefully selecting the measured parameters such that less memory can be used to store the pertinent measurement data. The contents of the memory can be transmitted directly to a base computer via an interface built into the instrument. Additionally, the instrument can use signature anaylsis to characterize the vibration of a machine. Vibration information contained within selected frequency bands can be recorded in the instrument's memory for subsequent analysis. Prior to storing the vibration data, the signal from the sensor is conditioned to enhance its reliability. Further, the components or modules of the unit are selectively energized to reduce power consumption. Other objects and advantages of the instrument will become apparent upon reading the detailed description together with the drawings described as follows.